High-rate Electrofluidic Directed Assembly of Nanoparticles on Insulating Surfaces

Abstract

The realization of commercial applications for nanoparticles, depends on the development of rapid and precise assembly placement of nanoparticles. Fluidic directed self-assembly is one approach to achieving a precise assembly on the surfaces. However, the assembly duration is long due to the slow particle migration in the suspension toward the substrate (limited by diffusion). Here, we introduce an enhanced fluidic assembly technique for the rapid and precise directed assembly of nanoparticles onto insulating patterned surfaces. In this method, electrophoresis is used to overcome the diffusion limit encountered when using fluidic self assembly. To accomplish electrophoretically enhanced fluidic self-assembly of nanoparticles onto a dielectric film, a conductive film is utilized below the substrate (insulating film) to enable eletrophoertic assembly. A DC electric field is applied between a patterned template and a counter electrode during assembly. The particles move towards the template under the influence of a DC electric field increasing the local particle concentration near the patterned template increase the speed of the assembly process by an order of magnitude or higher.